Devices used in physical therapy for working with disabilities and exercising are available in a variety of styles. Many of these devices include motors, springs, levers and platforms among other things.
One type of device that is frequently used is dish-shaped. The user stands, sits or kneels in it and exercises or develops balance and coordination by creating rocking motions. These devices usually have means by which the user maintains his or her position in it and those means usually are handles that the hands can grasp and footholds into which feet can be thrust. Other devices have eye bolts protruding from their surfaces to hold ropes or straps or they have other devices that the user can grasp. Dish-shaped exercise devices frequently have sharp edges or at least hard edges, and if the device is strong enough to maintain its structural integrity in use it is heavy.
In addition, prior devices are designed for use in a particular orientation or environment. Devices with rounded bottoms are intended to have the rounded bottoms supported on the floor and devices used for floatation do not have sufficient strength to be stepped or jumped upon if used out of the water. As a result, for each environment a differnt device is required.